The present invention relates generally to methods and circuits to enable identification of failure modes in light sources. More particularly, this invention pertains to circuits and methods for tracking light source usage time to facilitate failure mode recognition.
Light sources have useful lives generally ranging from thousands to millions of hours, depending on the type and configuration of the light source. Knowing an accumulated operating time of a failed light source is useful for warranty evaluation, end-of-life statistics, and failure mode evaluation. Particularly, end-of-life statistics for a light emitting diode based light source is not well known due to their long lifespans and relatively recent widespread use in various applications. Presently, accumulated operating time of a light source is measured only in laboratories, and those measurements are done with rudimentary methods utilizing stopwatches and estimations.